Improving Soybean (Glycine Max) Tolerance to AC 263,222 by Limiting Terminal Exposure

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Abstract
Field experiments were established to evaluate the effects of various band widths left open directly over the soybean row to improve soybean tolerance to AC 263,222 and chlorimuron applied POST, while maintaining weed control. Drop tubes with even fan tips extended below the spray boom to within 40 and 30 cm from the ground to obtain 5 and 10 cm open bands at the soybean terminals. AC 263,222 applied broadcast at 13, 18, and 36 g ai ha-1injured soybean 14, 16, and 32%, respectively, 3 DAT. AC 263,222 at 36 g ha-1applied with a 5-cm and 10-cm open band injured soybean 11 and 3%, respectively. Chlorimuron injury was 12% or less for all treatments. Metribuzin followed by AC 263,222 or chlorimuron was not more injurious to soybean than AC 263,222 or chlorimuron alone. Metribuzin PRE followed by 36 g ha-1AC 263,222 applied in a 10-cm open band controlled sicklepod and pitted morningglory 86 and 92%, respectively, 6 WAT. Sicklepod control was similar with open-band treatments compared to the same rate applied broadcast; however, 18 g ha-1AC 263,222 applied in a 10-cm open band provided less pitted morningglory control than the broadcast treatment. Soybean treated with herbicides in a band produced yields similar to or greater than soybean treated with the same herbicides broadcast. Metribuzin followed by 36 g ha-1AC 263,222 with a 10-cm open band resulted in a soybean yield of 2840 kg ha-1, which was greater than any other herbicide treatment and equivalent to the weed-free check.